Waveguide feed networks that can transmit left hand and right hand circularly polarized signals through circular waveguides and also can receive left hand and right hand circularly polarized signals from circular waveguides may require two transmit ports and two receive ports with good isolation between the ports. The waveguide feed networks may require filtering to provide the required isolation between the ports. Transmitter circuits may be coupled to transmit ports and receiver circuits may be coupled to the receive ports for transmitting and receiving the signals.
The waveguide feed network may be coupled to circular waveguides to implement a transformation from a linearly polarized signal at a transmit port to one of the left hand circularly polarized signal or right hand circularly polarized signal at the circular waveguide. Alternatively, the waveguide feed network may implement a transformation from one of the left hand circularly polarized signal or right hand circularly polarized signal at the circular waveguide to a linearly polarized signal at a receive port. This can make the design of an integrated waveguide feed network for transmitting and receiving signals with both left hand circular polarization and right hand circular polarization very complex.
In view of the foregoing, low complexity compact waveguide feed networks are required.